Spark-plug



Patented Mar. 1. 1921.

J. R. AYOTTE.

SPARK PLUG. APPLICATION FILED JULY'9, I9I9.

UNITED STATES- PATENT OFFICE.

JOSEPH RENE AYO'ITE, or CHICAGO, ILLfNoIs, ASSIGNOROF ONE-HALF T0 JULES x.

RIVARID.

SPARK-PLUG.

Specification of Letters Patent.

Patented Mar. 1 1921.

Application filed July 9, 1919. Serial at. 309,609.

To all whom z'tmay concern:

Be it known that I, J OSEPH Rnmt AYOTTE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.

This invention relates to improvements in spark plugs.

One of the objects of the invention is to generally improve spark plugs.

Another object is to increase the efficiency and reduce the cost of construction by fashioning the parts in such manner that they may readily be duplicated by operation of automatic machinery and by reducing the number of parts required.

Other, further and more specific objects of the invention will become readily apparent, to persons skilled in the art, from a consideration of the following description when taken in conjunction with the drawing, wherein Figure 1 is a central section of the improved spark plug.

Fig. 2 is a bottom plan view.

Fig. 3 is an enlarged cross section taken on line 3--3 of Fig: 1.

Fig. 4 is a fragmentary enlarged section through a composite gasket, before pressure is applied thereto, after assembling the parts.

Fig. 5 is ,a longitudinal central section of the insulating core.

Fig. 6 is a plan view of the copper ring, a. part of the gasket,before assembling.

Fig. 7 is a modified form of Fig. 3.

Fig. 8 shows the first step in making the hood of the stem of which the clamping screw is a part, shown at the top of Fig. 1.

Fig. 9 shows the second step in the manufacture of this structure.

In all the views the same refe ence characters are employed to indicate 1111113.! parts.

A shelllO and threaded gland 11 are not materially unlike those parts of any plug of standard construction. The core 12 is similar to cores that have heretofore been made, with the exception that the bottom end is tapered, as "at 13, and fluted, as at 14. The fiuting provides a strong ribbed terminal end and the taper permits the use of a minimum quantity of insulating material Without re ducing the mechanical strength of this part of the core, thereby allowing a larger sepaend of the core and the skirt ration between the core and the inner'bore of the shell. The shoulders 15 and 16 of the,

core are for holding the .core securely between the shell and gland. 'Theshoulder 17 at the top end of the core is intended for the purpose of securing the hood 18in place thereon. The central longitudinal bore 19 of the core is somewhat larger than the central conductor 20 thereof, so that the central conductor may be cemented in place throughout the entire length of the core, as by a layer ,of cement 21. The upper end of the conductor 20 is split to provide two separated terminals 22 and 23. These parts are spread apart to produce a head that will mechanically hold the centralconductor 20, in addition to the adhesive effect of the cement 21. These terminal ends also provide two sparking points for cooperation with the part 24 of the hood. spark gap is thus provided between the upper ends 22 and 23, of the central conductor 20, and the part 24 of the overlying hood. The horizontal part 24 of the hood, the screw stem 25 and the skirt 26 are made of one integral piecef The piece of stock, substantially a rod, and preferably of a very ductile material, such as copper or the like, is threaded, as at 25, and then the other end is swaged or laterally upset into disk form, as

at 26, more clearly shown in Fig. 8, and subsequently the disk is bent, as shown in Fig. 9, to provide the upper horizontal part 24 of the hood and the shoulder 27, which rests upon the shoulder 18 of the core, so as to space apart the part 24 and the ends 22 and 23 of the central conductor to provide a spark gap. When this structure is in the form shown in Fig. 9, it is placed upon the under the shoulder, as at 29, as by spinning, or the like. The shoulder 27 determines the width of the spark gap space between the part 24 and the bifurcated end of the core 20. The skirt '26 is preferably a neat fit over the shoulder 18 of the core and the 'upper surface of the part 24 is preferably roughed by a series of relatively small protuberances 30, which may be made therein when the disk 26 is swaged up into form from a part of the rod, of which the screw stem 25 was a portion, or instead of swaging it into prot uberances, as shown, a roughened surface similar to that shown! in Fig.

7, indicated by 31, preferably in tlie form A reinforcing 75 part is tucked 95 of nurling, may be substituted, The object ,oflvroughening the surface is. to more securely hold the current conducting wire between the parts 24 and the clamping nut I 32, which isscrewed over the stem 25.

theasbestos, or other fibrous ring'36, is placed over the top of the copper ring. lrVhen pressure is applied the yielding fibrous ma- -terial will become embedded .in the interd'ental space between. the teeth 35 of the i copper ring 3 and thus the parts will be a single structure.

heldtogether so that when the parts are subsequently dismantled or taken apart, the rings of the gasket 33 will hold-together as This form of structure is much cheaper than that usually :made in ,which separate operations are required to i, proximity with the lower end of the central unite the fibrous ring and the copper ring into a single structure.

An electrode 37 is secured to the lower end 38 of the shell lO-and projects into close ling 'the' parts, the copper ring 34 with conductor 20 as usual in structures of this character and between these two" electrodes the operative igniting spark of the plug is produced. y g

Having described my invention, what .1 claim is 1. A spark plug having in combinative association an insulating core with an annular axial perforation; a central. conductor passing through the core, having its'upper projecting end slit and separated to provide a head and a plurality of spark gap terminals, and a hood supported on the upper end of the core and spaced'apart from said terminals.

2. In a spark plug a structure providing a threaded stem at one end laterally expanded and formed into a hood at the'other end'with the top surface of the hood roughened, in combinative association with a binding nut on the said stem.

3. An article of manufacture, a spark plug, having in combmative association a shell; a core therein, the lowerpart of the core being tapered and longitudinally fluted toward its end. 4

In testimony whereof I hereunto subscribe my name.

JOSEPH RENE AYQTTE. 

